PRODUCTPREVIEW
1
FEATURES APPLICATIONS
DESCRIPTION
bq78PL114
www.ti.com
................................................................................................................................................................................................. SLUS850 – AUGUST 2008
PowerLAN™ Master Gateway Battery Management ControllerWith PowerPump Cell Balancing
•Portable Medical Instruments and Test23
•Designed for Managing up to 10 Series Cell
EquipmentBattery Systems
•Mobility Devices (E-Bike)•SmartSafety Features:
•Uninterruptible Power Supplies and Hand-Held– Prevention: Optimal Cell Management
Tools– Diagnosis: Improved Sensing of CellProblems
– Fail Safe: Detection of Event Precursors
The bq78PL114 master gateway battery controller is•Rate-of-Change Detection of All Important Cell
part of a complete Li-Ion control, monitoring, andCharacteristics:
safety solution designed for large series cell strings.– Voltage
The bq78PL114, along with PowerLAN cell monitors,– Impedance
provides complete battery system control,communications, and safety functions for a structure– Cell Temperature
of four to 10 series cells. This PowerLAN system•PowerPump Precision Cell Balancing
provides simultaneous, synchronized voltage andTransfers Charge Efficiently From Cell to Cell
temperature measurements using one-ADC-per-cellDuring All Operating Conditions, Resulting in
technology. Voltage measurements are alsoLonger Run Time and Cell Life
synchronized with pack current measurements,eliminating system-induced noise from•High-Resolution 18-Bit Integrating Delta-Sigma
measurements. This allows the precise, continuous,Coulomb Counter for Precise Charge-Flow
real-time calculation of cell impedance under allMeasurements and Gas Gauging
operating conditions, even during widely fluctuating•Multiple Independent Δ-ΣADCs: One-per-Cell
load conditions.Voltage, Plus Separate Temperature, Current,
PowerPump technology transfers charge betweenand Safety
cells to balance their voltage and capacity. Balancing•Simultaneous, Synchronous Measurement of
is possible during all battery modes: charge,Pack Current and Individual Cell Voltages
discharge, and rest. Highly efficient charge-transfer•Very Low Power Consumption: < 250 µA
circuitry nearly eliminates energy loss while providingActive, < 150 µA Standby, < 40 µA Ship, and
true real-time balance between cells, resulting inlonger run-time and improved cycle life.< 1 µA Undervoltage Shutdown•Accurate, Advanced Temperature Monitoring
Temperature is sensed by up to six external sensors.of Cells and MOSFETs With up to Six Sensors This permits accurate temperature monitoring of eachcell individually. Firmware is then able to compensate•Fail-Safe Operation of Pack Protection
for the temperature-induced effects on capacity,Circuits: Up to Three Power MOSFETs and
impedance, and OCV on a cell-by-cell basis, resultingOne Secondary Safety Output (Fuse)
in superior charge/ discharge and balancing control.•Fully Programmable Voltage, Current, Balance,
External MOSFET control inputs provide user-and Temperature-Protection Features
definable direct hardware control over MOSFET•External Inputs for Auxiliary MOSFET Control
states. Smart control prevents excessive current•Smart Battery System 1.1 Compliant via
through MOSFET body diodes. Auxiliary inputs canbe used for enhanced safety and control in largeSMBus or SPI Interface With SHA-1
multicell arrays.Authentication Option
1
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of TexasInstruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
2PowerLAN is a trademark of Texas Instruments.3Battery Wizard is a trademark of Lenmar Enterprises, Inc.
PRODUCT PREVIEW information concerns products in the
Copyright © 2008, Texas Instruments Incorporatedformative or design phase of development. Characteristic data andother specifications are design goals. Texas Instruments reservesthe right to change or discontinue these products without notice.
PRODUCTPREVIEW
DESCRIPTION (CONTINUED)
FLASH
PRE
CHG
EFCID
EFCIC
SMBus
DSG
SMBCLK
SMBDAT
SPROT
SPI-DI
CSBAT
SPI-DO
CSPACK
SPI-CLK
GPIO 6
CELL 4
Voltage
Temp
Balance
SPI
SELECT
V4
PUMP4
XT4
CELL 3
Voltage
Temp
Balance
V3
PUMP3
XT3
CELL 2
Voltage
Temp
Balance
V2
PUMP2
XT2
CELL 1
Voltage
Temp
Balance
2.5VLDO
V1
PUMP1
VLDO1
XT1
Watchdog
Coulomb Counter CCBAT
CCPACKCurrent A/D
Core / CPU
Measure
I/O
Safety
SRAM
RSTN
Internal
Temperature
RISC
CPU
Internal
Oscillator
Reset
Logic
First-LevelSafety
and
FET Control
Second-Level
Safety
LED1–5,
LEDEN
B0320-02
PowerLAN
Communication
Link
P-LAN
bq78PL114
SLUS850 – AUGUST 2008 .................................................................................................................................................................................................
www.ti.com
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foamduring storage or handling to prevent electrostatic damage to the MOS gates.
The bq78PL114 is completely user-configurable, with parametric tables in flash memory to suit a variety of cellchemistries, operating conditions, safety controls, and data reporting needs. It is easily configured using thesupplied Battery Wizard™ graphical user interface. The device is fully programmed and requires no algorithm orfirmware development.
Figure 1. bq78PL114 Internal Block Diagram
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PRODUCTPREVIEW
bq76PL102 Cell
MonitorWith
PowerPump
Balancing
PowerLAN
Communication
Link
PowerLAN
MasterGateway
BatteryController
bq78PL114
Pack
Positive
Pack
Negative
Example8-cellconfigurationshown
–+
SMBus
RSENSE
PackProtection
CircuitsandFuse
B0332-01
bq76PL102 Cell
MonitorWith
PowerPump
Balancing
bq78PL114
www.ti.com
................................................................................................................................................................................................. SLUS850 – AUGUST 2008
Figure 2. Example PowerLAN Multicell System Implementation
ORDERING INFORMATION
(1)
Quantity,Cell Communi- Package TemperatureProduct Package Ordering Number TransportConfiguration
(2)
cations Designator Range
Media
250, tapebq78PL114RGZT-8S
and reelbq78PL114 3 to 8 series cells SMBus
2500, tapebq78PL114RGZR-8S
and reel250, tapebq78PL114RGZT-10S
(3)
and reelQFN-48, 7-mm – 40 ° C tobq78PL114 3 to 10 series cells SMBus RGZ× 7-mm 85 ° C
2500, tapebq78PL114RGZR-10S
(3)
and reel250, tapebq78PL114RGZT-12S
(3)
and reelbq78PL114 3 to 12 series cells SMBus/SPI
2500, tapebq78PL114RGZR-12S
(3)
and reel
(1) Authentication options are also available; contact TI for additional information.(2) For configurations consisting of more than four series cells, additional bq76PL102 parts must be used.(3) Some historical data storage limits exist for the -10S and -12S versions.
Copyright © 2008, Texas Instruments Incorporated Submit Documentation Feedback 3
Product Folder Link(s): bq78PL114
PRODUCTPREVIEW
AVAILABLE OPTIONS
P0023-16
bq78PL114
RGZPackage
(TopView)
CHG
SDO0
DSG
SDI1
PRE
P1N
EFCIC
P2S
EFCID
P2N
CCBAT
SDO2
CCPACK
SDI3
VLDO1
P3S
CSBAT
P3N
CSPACK
P4S
OSCI
P4N
OSCO
P-LAN
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
LED5
VSS
LED4
V1
LED3
XT1
LED2
XT2
LED1
V2
LEDEN
VLDO2
SPROT
V3
SELECT
XT3
SPI-DO
XT4
SPI-DI
V4
SPI-CLK
SMBDAT
RSTN
SMBCLK
36
35
34
33
32
31
30
29
28
27
26
25
48
47
46
45
44
43
42
41
40
39
38
37
ThermalPad
bq78PL114
SLUS850 – AUGUST 2008 .................................................................................................................................................................................................
www.ti.com
Figure 3. bq78PL114 Pinout
TERMINAL FUNCTIONS
NAME NO. TYPE
(1)
DESCRIPTION
CCBAT 6 IA Coulomb counter input (sense resistor), connect to battery negativeCCPACK 7 IA Coulomb counter input (sense resistor), connect to pack negativeCHG 1 O Charge MOSFET control (active-high, enables current flow)CSBAT 9 IA Current sense input (safety), connect to battery negativeCSPACK 10 IA Current sense input (safety), connect to pack negativeDSG 2 O Discharge MOSFET control (active-high, low opens MOSFET)EFCIC 4 I External charge MOSFET control inputEFCID 5 I External discharge MOSFET control inputLED1 32 IO LED1 – active-lowLED2 33 IO LED2 – active-lowLED3 34 IO LED3 – active-lowLED4 35 IO LED4 – active-lowLED5 36 IO LED5 – active-lowLEDEN 31 IO LEDEN – common-anode drive (active-high)OSCI 11 I External oscillator input (optional)OSCO 12 O External oscillator output (optional)
(1) I – input, IA – analog input, O – output, OA – analog output, OD – open-drain output, P – power
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PRODUCTPREVIEW
bq78PL114
www.ti.com
................................................................................................................................................................................................. SLUS850 – AUGUST 2008
TERMINAL FUNCTIONS (continued)
NAME NO. TYPE
(1)
DESCRIPTION
P1N 15 O Charge-balance gate drive, cell 1 northP2S 16 O Charge-balance gate drive, cell 2 southP2N 17 O Charge-balance gate drive, cell 2 northP3N 21 O Charge-balance gate drive, cell 3 northP3S 20 O Charge-balance gate drive, cell 3 southP4N 23 O Charge-balance gate drive, cell 4 northP4S 22 O Charge-balance gate drive, cell 4 southP-LAN 24 IO PowerLAN I/O to external bq76PL10x nodesPRE 3 O Pre-Charge MOSFET control (active-high.)RSTN 25 I Device reset, active-lowSDI1 14 I Connect to SDO0 via a capacitorSDI3 19 I Internal PowerLAN connection – connect to SDO2SDO0 13 O Requires 100-k Ωpullup resistor to VLDO1SDO2 18 O Internal PowerLAN connection – connect to SDI3SELECT 29 O Auxiliary SPI control output
(2)
SMBCLK 37 IO SMBus clock signalSMBDAT 38 IO SMBus data signalSPI-CLK 26 IO SPI port clock
(2)
SPI-DI 27 I SPI master-out-slave-in
(2)
SPI-DO 28 O SPI master-in-slave-out
(2)
SPROT 30 O Secondary protection output, active-high (FUSE)V1 47 IA Cell-1 positive inputV2 44 IA Cell-2 positive inputV3 42 IA Cell-3 positive inputV4 39 IA Cell-4 positive inputVLDO1 8 P Internal LDO-1 output, bypass with capacitorVLDO2 43 P Internal LDO-2 output, bypass with capacitorVSS 48 IA Cell-1 negative inputXT1 46 IA External temperature-sensor-1 inputXT2 45 IA External temperature-sensor-2 inputXT3 41 IA External temperature-sensor-3 inputXT4 40 IA External temperature-sensor-4 input– – P Thermal pad. Connect to VSS
(2) SPI functionality requires a firmware option, consult the factory for additional information.
Copyright © 2008, Texas Instruments Incorporated Submit Documentation Feedback 5
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PRODUCTPREVIEW
ABSOLUTE MAXIMUM RATINGS
(1)
bq78PL114
SLUS850 – AUGUST 2008 .................................................................................................................................................................................................
www.ti.com
over operating free-air temperature range (unless otherwise noted)
RANGE UNITS
T
A
Operating free-air temperature (ambient) – 40 to 85 ° CT
stg
Storage temperature – 65 to 150 ° CV4 – V3 Maximum cell voltage – 0.5 to 5.0 VV3 – V2 Maximum cell voltage – 0.5 to 5.0 VV2 – V1 Maximum cell voltage – 0.5 to 5.0 VV1 – VSS Maximum cell voltage – 0.5 to 5.0 VVoltage on LED1 – LED5, CCBAT,
(VSS – 0.5) toCCPACK, CSBAT, CSPACK, XT1, XT2,
Maximum voltage on any I/O pin VOSCI, OSCO, SDIx, SDOx, SPROT,
(VLDO1 + 0.5)P-LAN
(V2 – 0.5) toVoltage on XT3, XT4, LEDEN Maximum voltage range V(VLDO2 + 0.5)EFCIC, EFCID With respect to VSS – 0.5 to 5.5 VVoltage on SMBCLK, SMBDAT With respect to VSS – 0.5 to 6 VVoltage on PRE, CHG, DSG With respect to VSS – 0.5 to (VLDO1 + 0.5) VCurrent through PRE, CHG, DSG,
Maximum current source/sink 20 mALED1 – LED5, P-LANVLDO1 maximum current Maximum current draw from VLDO 20 mAJEDEC, JESD22-A114 human-body model, R = 1500 Ω, C =ESD tolerance 2 kV100 pFLead temperature, soldering Total time < 3 seconds 300 ° C
(1) Stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device. These are stress ratingsonly, and functional operation of the device at these or any other conditions beyond those indicated under "recommended operatingconditions" is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
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PRODUCTPREVIEW
ELECTRICAL CHARACTERISTICS
DC Characteristics
Voltage-Measurement Characteristics
Current-Sense Characteristics
Coulomb-Counter Characteristics
(1) (2)
bq78PL114
www.ti.com
................................................................................................................................................................................................. SLUS850 – AUGUST 2008
T
A
= – 40 ° C to 85 ° C (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
V
CELL
(1)
Operating range Cells balanced 2.3 4.5 VI
DD
Operating-mode current Measure / report state 250 µAI
STBY
Standby-mode current SMBCLK = SMBDAT = L 100 µAI
SHIP
Ship-mode current 30 µAExtreme cell under voltage All cells < 2.7 V and any cell < ECUV setI
ECUV
(2)
1µAshutdown current pointV
OL
General I/O pins I
OL
< 4 mA 0 0.5 VV
OH
(3)
General I/O pins I
OH
< – 4 mA V
LDO1
– 0.1 VV
IL
General I/O pins 0.25 V
LDO1
VV
IH
General I/O pins 0.75 V
LDO1
V
(1) Device remains operational to 1.85 V with reduced accuracy and performancce.(2) All cells at 2.3 V at 25 ° C.(3) Does not apply to SMBus pins.
over operating free-air temperature range (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
Measurement range 2.5 4.5 VResolution < 1 mVAccuracy ± 3 mV
over operating free-air temperature range (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
Measurement range
(1)
– 0.2 0.2 VInput offset ± 50 µVResolution 18 µV± 18 µVAccuracy
(2)
± 0.1% ofreading
(1) Default range. Corresponds to ± 40 A using a 5-m Ωsense resistor. SBData limits the reported current range to ± 32 A.(2) After calibration. Accuracy is dependent on system calibration and temperature coefficient of sense resistor.
over operating free-air temperature range (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
Intergral nonlinearity 0.008%Snap-to-zero (deadband) ± 100
(3)
µV
(1) Shares common input with Current Sense section(2) After calibration. Accuracy is dependent on system calibration and temperature coefficient of sense resistor.(3) Corresponds to 20 mA using 50-m Ωsense resistor
Copyright © 2008, Texas Instruments Incorporated Submit Documentation Feedback 7
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PRODUCTPREVIEW
Current Sense (Safety) Characteristics
(1)
Internal Temperature Sensor Characteristics
(1)
External Temperature Sensor(s) Typical Characteristics
(1)
SMBus Characteristics
(1)
bq78PL114
SLUS850 – AUGUST 2008 .................................................................................................................................................................................................
www.ti.com
over operating free-air temperature range (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
Measurement range – 0.325 0.325 VShort-circuit detection 10Resolution mVOvercurrent detection, charge and discharge 1.25
(1) Post calibration: Dependent on system calibration and temperature coefficient of sense resistor. Uncertainty 1.5 LSB.
over operating free-air temperature range (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
Measurement range – 30 85 ° CResolution 0.1 ° CAccuracy
(1)
– 30 ° to 85 ° ± 1 ° C
(1) After calibration.
over operating free-air temperature range (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
Measurement range
(2)
– 40 90 ° CResolution 0.2 ° C25 ° ± 1Accuracy
(3)
° C0 ° to 85 ° ± 2
(1) Typical for dual diode (MMBD4148 or equivalent) external sensor using recommended circuit.(2) Range of diode sensors may exceed operational limits of IC and battery cells.(3) Typical behavior after calibration, final result dependent on specific component characteristics.
over operating free-air temperature range (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
V
IL
Input low voltage 0 0.8 VV
IH
Input high voltage 2.1 5.5 VV
OL
(2)
Output low voltage 350- µA sink current 0 0.4 VC
I
Capacitance, each I/O pin 10 pFf
SCL
SCLK nominal clock frequency T
A
= 25 ° C 100 kHzV
BUS
5 V nominal 13.3 45.3R
PU
(3)
Pullup resistors for SCLK, SDATA k ΩV
BUS
3 V nominal 2.4 6.8
(1) SMBus timing and signals meet the SMBus 2.0 specification requirements under normal operating conditions. All signals are measuredwith respect to PACK-negative.(2) Parameter not tested in production.(3) Pullups are typically implemented external to battery pack, and are selected to meet SMBus requirements.
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PRODUCTPREVIEW
bq78PL114
PowerLAN
GatewayBattery
Management
Controller
RPRE
+PACK+
–
SPI-DI
SMBCLK
SMBDAT
RSENSE
PACK–
XT1–4
Temperature
Sensor(typ.)
SPROT
GPIO0–5
Typicalsix-cellconfigurationshown.
AdditionalcellsaddedviaPowerLANconnection.
Somecomponentsomittedforclarity.
SPI-DO
V2
V3
V4
V1
VLDO2
CRFI
VLDO1
RSTN
SDO2
SDI3
EFCID
EFCIC
Oneof4external
sensorsshown
SPI-CLK
P-LAN
6
CELL 6
CELL 5
V2
V1
SDI1
SDO0
SELECT
Level-ShiftCircuits
CHG
DSG
PRE
ESDProtection
SMBus SPI AuxFET
Control
TAB
VSS
CSBAT
CCBAT
CCPACK
CSPACK
CellBalancing
Circuits
CellBalancingCircuits
bq76PL102
CELL 4
CELL 3
CELL 2
CELL 1
S0342-02
bq78PL114
www.ti.com
................................................................................................................................................................................................. SLUS850 – AUGUST 2008
Figure 4. bq78PL114 Simplified Example Circuit Diagram
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PRODUCTPREVIEW
FEATURE SET
Primary (First-Level) Safety Features
Secondary (Second-Level) Safety Features
Charge Control Features
Gas Gauging
LED Display
bq78PL114
SLUS850 – AUGUST 2008 .................................................................................................................................................................................................
www.ti.com
The bq78PL114 implements a breadth of system protection features which are easily configured by thecustomer. First-level protections work by controlling the MOSFET switches. These include:•Battery cell over/undervoltage protection•Pack over/undervoltage protection•Charge and discharge overcurrent protection•Short-circuit protection•External MOSFET control inputs (EFCIx) with programmable polarity•Up to four external temperature inputs for accurate cell and MOSFET monitoring•Watchdog timer protection•Brownout detection and protection against extreme pack undervoltage
The bq78PL114 can detect more serious system faults and activate the SPROT pin, which can be used to openan in-line chemical fuse to permanently disable the pack. Secondary optional features include•Fully independent of first-level protections•SmartSafety algorithms for early detection of potential faults– Temperature abnormalities (variances, extremes, rate of change, etc.)– Disconnected cell voltage inputs– Cell imbalance exceeds safety limits– Impedance rise due to cell or weld strap fault•MOSFET failure or loss of MOSFET control•Safety overvoltage, pack and cell•Safety overtemperature, limits for both charge and discharge•Safety overcurrent, charge and discharge•Failed current measurement, voltage measurement, or temperature measurement
•Meets SMBus 2.0 and Smart Battery System (SBS) Specification 1.1 requirements•Active cell balancing using patented PowerPump technology, which eliminates unrecoverable capacity lossdue to normal cell imbalance•Balancing-current monitoring to detect cell problems•Simultaneous, synchronous measurement of all cell voltages in a pack•Simultaneous, synchronous measurement of pack current with cell voltages•Reports target charging current and/or voltage to an SBS Smart Charger•Reports the chemical state-of-charge for each cell and pack•Supports precharging and zero-volt charging with separate MOSFET control•Programmable, Chemistry-specific parameters•Fault reporting
•The bq78PL114 accurately reports battery cell and pack state-of-charge (SOC). No full charge/dischargecycle is required for accurate reporting.•State-of-charge is reported via SMBus and optional LED display.•18-bit integrating delta-sigma ADC coulomb counter, with programmable snap-to-zero value
•The bq78PL114 drives a three- to five-egment LED display in response to a pushbutton (LEDEN) input signal.Each LED pin can sink up to 10 mA.
10 Submit Documentation Feedback Copyright © 2008, Texas Instruments Incorporated
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PRODUCTPREVIEW
Lifetime Data Logging (Readable via SMBus or SPI)
Forensic Data Logging (Readable via SMBus or SPI)
Power Modes
OPERATION
bq78PL114
www.ti.com
................................................................................................................................................................................................. SLUS850 – AUGUST 2008
•Recording of faults, events, anomalies, minimum and maximum values•Maximum/minimum temperature•Maximum/minimum pack voltage•Maximum/minimum cell voltages•Maximum charge and discharge currents
•Last known full capacity of each cell•Cycle count and/or cumulative number of ampere-hours delivered by the battery•Battery pack status: being charged, discharged, or at rest•Balancing effort required by each bank of cells to maintain balance•Information for each cell bank for period leading up to failure•Last 10 failures causing first-level safety action•Forensic data up-loadable to host CPU via SMBus or SPI•Forensic data recording of anomalies and events
•Normal Mode: The bq78PL114 performs measurements and calculations, makes decisions, and updatesinternal data approximately once per second. All safety circuitry is fully functional in this mode.•Standby Mode: The bq78PL114 performs as in normal mode, but at a dramatically reduced rate to lowerpower consumption at times when the host computer is inactive or the battery system is not being used. Allsafety circuitry remains fully functional in this mode.•Ship Mode: The bq78PL114 disables (opens) all the protection MOSFETs, and continues to monitortemperature and voltage, but at a reduced measurement rate to dramatically lower power consumption.Environmental data is saved in flash as a part of the historical record. Safety circuitry is disabled in this mode.The device does not enter this power state as a part of normal operation; it is intended for use after factoryprogramming and test. Entry occurs only after a unique SMBus or SPI command is issued. Exit occurs whenthe SMBus or SPI lines return to an active state.•Extreme Cell Undervoltage (ECUV) Shutdown Mode: In this mode, the bq78PL114 draws minimal currentand the charge and discharge protection MOSFETs are disabled (opened). The precharge MOSFET remainsenabled when a charge voltage is present. Safety circuitry is disabled in this mode. The device does not enterthis mode as a part of normal operation; it enters this state during extreme cell undervoltage conditions(ECUV). The ECUV threshold is fully programmable below 2.7V.CURRENT OVERCURRENTSTATE ENTRY CONDITION EXIT CONDITIONDRAW (Typ) PROTECTION
Normal operation as determined by Firmware directed to the followingActive < 250 µA Fully active
firmware operating modesNo load current flowing forStandby < 150 µA Fully active Load activitypredetermined timeShip < 40 µA Not active Protected SMBus or SPI command SMBus or SPI becomes activeNot activeExtreme cell Vcell charge above ECUV recovery< 1 µA (precharge Enabled when Vcell < ECUVundervoltage threshold (2.7 V/cell typical)enabled)
The bq78PL114 battery management controller serves as the master controller for a Li-Ion battery systemconsisting of up to 10 cells in series. Any number may be connected in parallel; other system or safety issueslimit the number of parallel cells. The bq78PL114 provides extraordinarily precise state-of-charge gas gaugingalong with first and second level pack safety functions. Voltage and current measurements are performedsynchronously and simultaneously for all cells in the system, allowing a level of precision not previously possible
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PRODUCTPREVIEW
PowerLAN Communication Link
Safety
Cell Balancing
bq78PL114
SLUS850 – AUGUST 2008 .................................................................................................................................................................................................
www.ti.com
in battery management. Temperature is measured by up to four additional external temperature sensors, for atotal of five independent measurement points. (Additional cell temperature sensors are available in remotebq76PL102 dual-cell battery monitors.) Coulomb counting is captured continuously by a dedicated 18-bitintegrating delta-sigma ADC in the bq78PL114. The CPU in the bq78PL114 is also responsible for system datacalculations, black-box forensic data storage, and communicating parameters via the SMBus or SPI interface.
PowerLAN technology is Texas Instruments ’ patented serial network and protocol designed specifically forbattery management in a multicell system environment. The PowerLAN link is used to initiate and reportmeasurements of cell voltage and temperature, and control cell balancing. The bq78PL114 serves as the mastercontroller of the PowerLAN link and can interface to multiple bq76PL102 dual-cell battery monitors, whichmeasure and balance additional cells. The bq78PL1114 monitors the first three or four cells, and bq76PL102scan be added to monitor more series cells.
The PowerLAN link isolates voltages from adjacent bq76PL102 devices to permit high-voltage stack assemblywithout compromising precision and accuracy. The PowerLAN link is expandable to support up to 10 cells inseries. Each bq76PL102 handles voltage and temperature measurements, as well as balancing for two cells. ThePowerLAN link provides high ESD tolerance and high immunity to noise generated by nearby digital circuitry orswitching currents. Each bq76PL102 has both a PowerLAN input and PowerLAN output: Received data isbuffered and retransmitted, permitting high numbers of nodes without loss of signal fidelity. Signals arecapacitor-coupled between nodes, providing dc isolation.
Unique in the battery-management controller market, the bq78PL114 simultaneously measures voltage andcurrent using independent and highly accurate delta-sigma ADCs. This technique removes virtually all systemicnoise from measurements, which are made during all modes of battery operation: charge, discharge, and rest.The bq78PL114 also directs all connected bq76PL102 dual-cell battery monitors to measure each cell voltagesimultaneously with the bq78PL114 measurements. Battery impedance and self-discharge characteristics arethus measured with an unprecedented level of accuracy in real time. The bq78PL114 applies this preciseinformation to SmartSafety algorithms to detect certain anomalies and conditions which may be indicative ofinternal cell faults, before they become serious problems.
The bq78PL114 uses its enhanced measurement system to detect system faults including cell under- andovervoltage, cell under- and overtemperature, system overvoltage, and system overcurrent. First-level safetyalgorithms first attempt to open the MOSFET safety switches. If this fails, second-level safety algorithms ctivatethe SPROT output, normally used to open a fuse and provide permanent, hard protection for the systems.External MOSFET control inputs with programmable polarity can also be used to operate the safety MOSFETsunder control of user supplied circuitry. The bq78PL114 continuously monitors these inputs. If any MOSFET failsto open when commanded; the 2
nd
level safety algorithms also activate the SPROT output. All first- andsecond-level safety algorithms have fully programmable time delays to prevent false triggering.
Patented PowerPump cell balancing drastically increases the useful life of battery packs by eliminating the cyclelife fade of multi-cell packs due to cell imbalance. PowerPump efficiently transfers charge from cell to cell, ratherthan simply bleeding off charging energy as heat as is typically done with resistive-bleed balancing circuits.Balancing is configurable and may be performed during any battery operational modes: charge, discharge, orrest. Compared to resistive bleed balancing, virtually no energy is lost as heat. The actual balance current isexternally scalable and can range from 10 mA to 1 A (100 mA typical) depending on component selection andsystem or cell requirements.
A variety of techniques, such as simple terminal voltage, terminal voltage corrected for impedance andtemperature effects, or state-of-charge balancing, is easily implemented by the bq78PL114. In some cases,chemistry-specific algorithms are available. By tracking the balancing required by individual cells, overall batterysafety is enhanced, often allowing early detection of soft shorts or other cell failures. Balancing is achievedbetween all cells within the pack as dynamically determined by the bq78PL114.
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PRODUCTPREVIEW
Outputs
Inputs
bq78PL114
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................................................................................................................................................................................................. SLUS850 – AUGUST 2008
Charge Control
The open-drain outputs CHG and PRE are ordinarily used to drive MOSFET transistors controlling charge to thecell stack. Charge or precharge mode is selected based on the present cell voltage compared to theuser-definable cell precharge, undervoltage, and temperature thresholds. When below these limits, the PREsignal is active and the CHG signal is inactive. This turns on the precharge MOSFET and is used to charge adepleted system through a current-limiting series resistor. When all cell voltages are above the limit and thetemperature is above the charge temperature minimum, then the CHG output also becomes active and enablesthe charge MOSFET to turn on, providing a high-current path between charger and battery cells.
The CHG and PRE MOSFET control outputs are both disabled (low) when any cell reaches the safety cutoff limitor temperature threshold. During active charging modes (and above cell voltage thresholds), the dischargeMOSFET is also enabled to avoid excessive heating of the body diode. Similarly, the charge MOSFET is activeduring discharge, provided current flow is in the correct direction and no safety violations are present.
The CHG and PRE outputs are intended to drive buffer transistors acting as inverting level shifters.
Discharge Control
The DSG output operates similarly to control-system discharging. It is enabled (high) by default. If a cell voltagefalls below a programmable threshold, or excessive current or other safety related fault is sensed, the DSGoutput is disabled (low) to prevent damage to the cells.
All facets of safely charging and discharging the cell stack are controlled by user-definable parameters whichprovide precise control over MOSFET states. Both system and cell over- and undervoltage limits are provided, aswell as programmable hysteresis to prevent oscillation. Temperature and current thresholds are also provided,each with independent timers to prevent nuisance activations.
LEDEN
LEDEN is a dual-function pin. One function is to provide output current to the LED display array. It also serves asan input that monitors for closure of a state-of-charge indicator (SOCi) push-button switch.
LED SOCi Outputs
LED1 – LED5 are current-sinking outputs designed to drive low-current LEDs. The LEDs can be activated by theLEDEN pin via a pushbutton switch. They can be configured (using SBS parameters) to operate in bar or dotmode and to use three to five LEDs to represent state-of-charge information.
Current Measurement
Current is monitored by four separate ADCs. All use the same very low-value sense resistor, typically either 5 or10 milliohms in series with the pack negative connection. CCBAT and CCPACK connections to the senseresistor use an R/C filter for noise reduction. (CSBAT and CSPACK are direct connections used for secondarysafety.) It is possible to use even lower values for the sense resistor in very high-current designs by employingexternal circuitry. Contact Texas Instruments directly for details.
A 14-bit delta-sigma ADC is used to measure current flow accurately in both directions. The measurements aretaken simultaneously and synchronously with all the cell voltage measurements, even those cells measured bybq76PL102 dual-cell battery monitors.
Coulomb Counting
A dedicated coulomb counter is used to measure charge flow with 18 bit precision in both directions by acalibrated, integrating delta-sigma ADC. This allows the bq78PL114 to keep very accurate state-of-charge (SOC)information and battery statistics. A small deadband is applied to further reduce noise effects. The coulombcounter is unique in that it continues to accumulate (integrate) current flow in either direction even as the rest ofthe internal microcontroller is placed in a very low power state, further lowering power consumption withoutcompromising system accuracy.
Copyright © 2008, Texas Instruments Incorporated Submit Documentation Feedback 13
Product Folder Link(s): bq78PL114
PRODUCTPREVIEW
COMMUNICATIONS
SMBus
SPI
bq78PL114
SLUS850 – AUGUST 2008 .................................................................................................................................................................................................
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Safety Current
Two additional ADCs are used to directly monitor for overcurrent or short-circuit current conditions, independentlyof the internal function. This provides a direct and rapid response to insure pack integrity and safe operation byopening the appropriate MOSFETs. These functions are implemented in hardware, and do not require firmwarefor functionality.
Voltage Measurement
Voltage measurement is performed by four independent delta-sigma ADCs which operate simultaneously andare triggered synchronously so that all voltages are read at precisely the same moment. The bq78PL114coordinates the attached bq76PL102 dual-cell battery monitors so they also perform their cell voltagemeasurements in sync with the bq78PL114 voltage and current measurements. Voltage measurements areconverted with better than 1 mV of resolution, providing superior accuracy. One-ADC-per-cell technology meansthat voltage is also measured simultaneously with current, permitting accurate, real-time cell impedancecalculation during all operating conditions. This technique also provides greatly enhanced noise immunity andfiltering of the input signal without signal loss.
Temperature Measurement
XT1 – XT4 are dedicated temperature inputs. Each external sensor consists of a low-cost silicon diode (dual diodein one package is recommended) and capacitor combination. XT1, multiplexed with the LED1 and LED2 inputs,is used to measure cells 1 and 3. XT2, multiplexed with the LED1 and LED2 inputs, is used to measure cells 2and 4. XT3 is a dedicated IC-temperature sensor, which should be placed near the bq78PL114 IC. XT4 isdedicated to protection-MOSFET temperature and governed by safety rules. The sensor attached to XT4 shouldbe placed near the pack-disconnect MOSFETs. Temperatures for cells 5 and above are measured by externalbq76PL102(s), and the temperature data is received by the bq78PL114 over the PowerLAN link for processing.The bq78PL114 can report all of these temperatures individually and as an average. A single internal, integratedsilicon sensor is also supplied in the bq78PL114.
Note that additional external temperature sensors can be added using bq76PL102 dual-cell battery monitorsoperating on the PowerLAN link. Each bq76PL102 contains one internal temperature monitor and two additionalexternal temperature-sensor inputs (in addition to the two cell-voltage measurements and cell balancing).
EFCIx
The external MOSFET control inputs are for user control of MOSFETs based on external circuitry and conditions.The polarity of the input signal is user programmable. Two modes of operation are possible. The first mode isused to implement additional hardware safety inputs, and is used to force the protection MOSFETs to an OFFstate. The polarity of the input signals is programmable. The inputs can also be used to control the MOSFETsdirectly through hardware, with no firmware operation required.
The bq78PL114 uses the industry-standard Smart Battery System ’ s two-wire System Management Bus (SMBus)communications protocol for all external communication. SMBus version 2.0 is supported by the bq78PL114, andincludes clock stretching, bus fault time-out detection, and optional packet error checking (PEC). For additionalinformation, see the www.smbus.org and www.sbs-forum.org Web sites.
The bq78PL114 provides a standard serial peripheral interface (SPI) port consisting of SELECT, SPI-DI, SPI-DO,and SPI-CLK signals. This port may be operated as a master or slave SPI port. A typical system configurationuses the bq78PL114 as a SPI slave device so that a host controller could access the various battery data usingthe industry-standard Smart Battery Data specification for content.
Alternatively, the SPI port may be operated as a master to allow the bq78PL114 to write selected system data toanother device for use in an autonomous application.
Contact Texas Instruments for additional SPI options and details.
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PRODUCTPREVIEW
Smart Battery Data (SBData)
bq78PL114
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................................................................................................................................................................................................. SLUS850 – AUGUST 2008
The data content and formatting of the bq78PL114 information conforms to the Smart Battery System ’ s (SBS)Smart Battery Data specification, version 1.1. See the SBS/SMBus site at www.sbs-forum.com for furtherinformation regarding these specifications.
This SBS Data (SBData) specification defines read/write commands for accessing data commonly required inlaptop computer applications. The commands are generic enough to be useful in most applications.
Because the bq78PL114 provides a wealth of control and battery information beyond the SBData standard, newcommand codes have been defined by Texas Instruments. In addition, new battery data features, such asstate-of-health, use newly defined extended SBData command codes. Standard SMBus protocols are used,although additional data values beyond those defined by the Smart Battery Data specification are employed. (Forexample, the bq78PL114 typically is used in a multicell battery system and may report individual cell voltages forup to 10 cells. The SBData command set only defines four cell-voltage registers.)
Copyright © 2008, Texas Instruments Incorporated Submit Documentation Feedback 15
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PRODUCTPREVIEW
SBS Standard Data Parameter List (Abridged)
(1) (2)
bq78PL114
SLUS850 – AUGUST 2008 .................................................................................................................................................................................................
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Command Data Type Descripotion
00 R/W word (unsigned) Manufacturer Access01 R/W word (unsigned) Remaining Capacity Alarm Level02 R/W word (unsigned) Remaining Time Alarm Level03 R/W word (unsigned) Battery Mode04 R/W word (unsigned) At Rate value used in AtRate calculations05 Read word (unsigned) At Rate Time to Full06 Read word (unsigned) At Rate Time to Empty07 Read word (Boolean) At Rate OK08 Read word (unsigned) Pack Temperature (maximum of all individual cells)09 Read word (unsigned) Pack Voltage (sum of individual cell readings)0A Read word (unsigned) Pack Current0B Read word (unsigned) Average Pack Current0C Read word (unsigned) Max Error0D Read word (unsigned) Relative State of Charge0E Read word (unsigned) Absolute State of Charge0F Read word (unsigned) Remaining Pack Capacity10 Read word (unsigned) Full Charge Capacity11 Read word (unsigned) Run Time to Empty12 Read word (unsigned) Average Time to Empty13 Read word (unsigned) Average Time to Full14 Read word (unsigned) Charging Current15 Read word (unsigned) Charging Voltage16 Read word (unsigned) Battery Status17 Read word (unsigned) Cycle Count18 Read word (unsigned) Design Capacity19 Read word (unsigned) Design Voltage1A Read word (unsigned) Specification Information1B Read word (unsigned) Manufacture Date1C Read word (unsigned) Serial Number1D – 1F Reserved20 Read block (string) Pack Manufacturer Name (31 characters maximum)21 Read block (string) Pack Device Name (31 characters maximum)22 Read block (string) Pack Chemistry23 Read block (string) Manufacturer Data24 – 2E Reserved2F R/W Block Optional Manufacturer Function 530 – 3B Reserved3C R/W word (unsigned) Optional Manufacturer Function 4 (Vcell 4)3D R/W word (unsigned) Optional Manufacturer Function 3 (Vcell 3)3E R/W word (unsigned) Optional Manufacturer Function 2 (Vcell 2)3F R/W word (unsigned) Optional Manufacturer Function 1 (Vcell 1)40 – 45 Unused46 – 47 Reserved48 – 4F Unused50 – 55 Reserved
(1) Parameters 0x00 – 0x3F are compatible with the SBDATA specification.(2) By default, the bq78PL114 initially responds to the SBData slave address < 0001 011R/W > (0x16, 0x17).
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................................................................................................................................................................................................. SLUS850 – AUGUST 2008
Command Data Type Descripotion
56 – 57 Unused58 – 5A Reserved5B – 5F Unused60 – 62 Reserved63 – 6F Unused70 Reserved71 – FF Unused
Copyright © 2008, Texas Instruments Incorporated Submit Documentation Feedback 17
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PRODUCTPREVIEW
REFERENCE SCHEMATIC (3 Series Cells)
bq78PL114
SLUS850 – AUGUST 2008 .................................................................................................................................................................................................
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PRODUCTPREVIEW
REFERENCE SCHEMATIC (8 Series Cells)
bq78PL114
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................................................................................................................................................................................................. SLUS850 – AUGUST 2008
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Product Folder Link(s): bq78PL114
PACKAGING INFORMATION
Orderable Device Status (1) Package
Type Package
Drawing Pins Package
Qty Eco Plan (2) Lead/Ball Finish MSL Peak Temp (3)
BQ78PL114RGZR PREVIEW QFN RGZ 48 2500 TBD Call TI Call TI
BQ78PL114RGZT PREVIEW QFN RGZ 48 250 TBD Call TI Call TI
(1) The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in
a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check
http://www.ti.com/productcontent for the latest availability information and additional product content details.
TBD: The Pb-Free/Green conversion plan has not been defined.
Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements
for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered
at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.
Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and
package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS
compatible) as defined above.
Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame
retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material)
(3) MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder
temperature.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is
provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the
accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and continues to take
reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on
incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited
information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI
to Customer on an annual basis.
PACKAGE OPTION ADDENDUM
www.ti.com 14-Aug-2008
Addendum-Page 1
IMPORTANT NOTICE
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